本文以二程的天理思想为主要论题，旨在说明二程的天理思想在理论背景、主要内容与理论视角方面的异同，并在此基础上回应二程研究中的部分重要问题。 
第一章主要说明二程天理思想的理论背景与问题意识。二程继承了宋初以来学者变古革新、重视宇宙论与本体论研究的学术风气，充分吸收了先秦以来儒道两家关于“天理”的思想资源，尤其重视关学对“理”“气”的研究，以此提出了自己具有革新性的“天理”思想。二程对“天理”的研究与重视具有对抗佛教功利性与虚无主义、清扫民间鬼神迷信的目的。 
第二章分别分析二程的“天理”“理”等概念的哲学内涵。程颢使用“天理”与“生生”“易”“道”“神”等概念共同说明包含形上与形下的宇宙整体的不同方面。其中，“天理”与“生生”具有更高的地位，“天理”强调这一整体具有的超越性与规律性，“生生”则强调创造性与运动性是这一整体的根本属性。程颢也使用“理”“天理”表示具体事物的存在根据、生化规律与道德规范，其是整体天理在局部的表现。程颐同样认为“天理”是宇宙整体的存在根据、生化动力与总的规定性，认为此“一理”根据不同事物的“分”表现为“殊理”，即具体事物的存在根据、变化规律与道德原则。二程对“天理”的理解在实然层面相似，在言说方式上具有较大差异。 
第三章从二程的“气论”入手分别论述二程的理气关系。程颢的“气”既表示人的身体与情感状态，也是构成形下世界的物质因素。两种“气”本质相同。气作为宇宙整体的物质性，与“神”“理”不可分论，天理决定了气生灭运动的总体趋势。气作为具体事物的物质性，因天理生生、对待的性质与自身的有限性表现出天理在局部特殊的规定性。局部的气会因其运化符合天理整体的规定性而顺利，反之则不顺。程颐早年对“气”的使用较少，多与经典诠释或他人问答有关。中年后，程颐多用“气”，其具有情感、禀赋、物质等多方面的含义，程颐以此解释自然现象、天人关系、心性关系等多方面的内容。在自然方面，程颐提出了一个由天理、阴阳二气、五行之气、具体之物组成的宇宙模型。在人的心性方面，程颐以“气”作为天理命之于人的中介与形式。归根结底，程颐将气与万殊之物统摄于天理之中。
第四章说明二程天理思想中表现出的、不同的功夫论与理论视角，并回应二程研究中关于天理的一些重要问题。程颢在论述有关天理的内容时重视“一本”“一体”感，以贯通形上与形下、主体与客体的宇宙整体作为出发点，在“一本”的视角中分析具体事物，在言说时强调整体的圆融与各部分的连通，通过万物一体的识仁功夫得天理。程颐对“天理”的论述体现出“穷理”的特色，其理论的出发点是具体现象的存在根据与合理性，重视万物之间的区别与分隔，通过穷理尽性的方式得天理。二人在宇宙本体论上的建构基本相同，在功夫论与理论视角上差异较大。牟先生批评程颐的天理“只存有不活动”值得商榷。
第五章作为全文结语，总结全文，并简要说明了二程天理思想呈现一定差异的原因。一方面，程颐更长、更丰富的学术经历使其思想体现更加细致丰富；另一方面，二程性格的差异以及对功夫体悟的差异也影响了二人对“天理”及相关问题的论述。

This article takes Cheng Yi and Cheng Hao’s Heavenly principle as the main topic, aiming to explain the similarities and differences in theoretical background, main content, and theoretical perspective of Cheng Yi and Cheng Hao’s thought of Heavenly principle, and to respond to some important issues in this field.
The first chapter mainly explains the theoretical background and problem consciousness when Cheng Yi and Cheng Hao’s proposed thought of Heavenly principle. Cheng Yi and Cheng Hao inherited the academic atmosphere of scholars' transformation and innovation since the early Song Dynasty, emphasizing the study of cosmology and ontology, fully absorbing the ideological resources of Confucianism and Taoism on "Heavenly Principle" since the pre-Qin period, especially emphasizing the study of "principles" and "Qi" by Zhang Zai, and thus proposing his own revolutionary "Heavenly Principle" thought. Cheng Yi and Cheng Hao’s research and emphasis on the "Heavenly Principle" has the purpose of fighting against Buddhist utilitarianism and nihilism, and cleaning up the superstition of superstition in normal people.
The second chapter analyzes the philosophical connotations of concepts such as "Heavenly Principle" and "reason" in Cheng Yi and Cheng Hao. Cheng Hao used concepts such as "Heavenly Principle", "Birth", "Yi", "Dao", "God" to jointly explain the different aspects of the universe as a whole, including both physics and metaphysics. Among them, "Heavenly Principle" and "Birth" have a higher status. "Heavenly Principle" emphasizes the transcendence and regularity of the whole universe, while " Birth " emphasizes creativity and mobility as the fundamental attributes of it. Cheng Hao also uses "reason" and "Heavenly Principle" to represent the existence basis and natural laws of specific things, which is the manifestation of the Heavenly Principle in a special context. Cheng Yi also believes that Heavenly Principle is the basis for the existence, natural power, and overall regularity of the universe as a whole. He believes that this "one principle" "one reason" is manifested as "special principles" based on the "position" of different things, that is, the basis for the existence, laws of change, and moral principles of specific things. Cheng Yi and Cheng Hao's understanding of "Heavenly Principle" is similar, but there are some significant differences in the way they spoke and understood it.
The third chapter starts with the "Qi" theory of Cheng Yi and Cheng Hao, and discusses the relationship between principle and Qi. Cheng Hao's "Qi" not only represents a person's physical and emotional state, but also the material factors that constitute the physical world. The two types of "Qi" are essentially the same. As the materiality of the universe as a whole, Qi is inseparable from the "God" and "principles", and the Heavenly Principle determine the overall trend of the movement of Qi's birth and death. Qi, as the materiality of specific things, exhibits the unique local regularity of natural principles due to their inherent nature and limitations of circumstance. Qi will flow smoothly due to its conformity with the overall laws of heaven, and vice versa. In Cheng Yi's early age, he used "Qi" in a relatively limited way, which is mostly related to classic interpretations or other people's question. After middle age, Cheng Yi used "Qi" widely, which had various meanings such as emotions, endowments, and materials. Cheng Yi used this to explain various aspects of natural phenomena, the relationship between the world and human, and the relationship between mind and the principle. In terms of nature, Cheng Yi proposed a universe model composed of heavenly principle, Yin and Yang, five element, and specific objects. In terms of human nature, Cheng Yi uses "Qi" as the intermediary and form of the order of world and destiny of humans. In the final analysis, Cheng Yi governed the Qi and the myriad things within the Heavenly Principle.
The fourth chapter explains the differences of "Gong Fu" theories and theoretical perspectives of Cheng Yi and Cheng Hao, and responds to some important issues related to Heavenly Principle in Cheng Yi and Cheng Hao’s research. Cheng Hao attached great importance to the "one" when discussing the content of heavenly principle. Starting from the perspective of the "one ", he analyzed specific things from the perspective of the "one ", emphasizing the integration of the whole and the connection of various parts, and obtained heavenly principle through the benevolence of the unity of all things. Cheng Yi's discourse on Heavenly Principle reflects the characteristics of "pursuing principles". The starting point of his theory is the basis and law of the existence of specific phenomena, emphasizing the differences and separations between all things, and obtaining Heavenly Principle through pursuing specific principles. The construction of the ontology of the universe by Cheng Yi and Cheng Hao is basically the same, but there are significant differences in the perspective of "Gong Fu" and theoretical perspective. Mou Zongsan's criticism of Cheng Yi's natural principle as "only existing but not active" is doubtful.
The fifth chapter, as the conclusion of the entire text, briefly explains the reasons for the differences in the Heavenly Principle thoughts of Cheng Yi and Cheng Hao. On the one hand, Cheng Yi's longer and richer academic experience has made his ideological expression more detailed and richer; On the other hand, the differences in Cheng Yi and Cheng Hao’s personality and understanding of Gong Fu also influenced their discourse on "Heavenly Principle" and related issues.